VOLVO
CEM-6C33 - Movement sensor. Signal missing
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsC30 (2007–2013), C30 Electric (2011–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The CEM cannot communicate with the rear mass movement sensor (MMS) or with the movement sensor (IMS). The fault code is then set, and the alarm cannot react to movement in the rear part of the passenger compartment.
Possible causes
- Internal fault in the rear motion sensor (MMS)
- Internal error in the movement sensor (IMS)
What you can do
- 1Check that the connector to the rear sensor is secure and free from corrosion
- 2Use a multimeter to check that the signal wires between the sensor and the central electronic module have no break and no contact with ground or voltage
- 3Check that the reduced alarm function is not activated, as the car will then not react to the sensors
- 4Lock the car, open a rear side window and move a hand in the back of the cabin; the alarm should sound. Silence it with the remote unlock button
- 5If no other fault is found, the sensor should be replaced, which a workshop should do
Symptoms you may notice2
- Alarm does not respond to the sensor
- Message in the display
General guidance for car owners. Diagnosis on the car can point to a different cause.